1. Field of the Invention
This invention relates to an automatic door opener and relates particularly but not exclusively to such for use on garage doors of the roller shutter type or the tilt type.
2. Statement of the Prior Art
When automatic door openers are provided on doors such as garage doors it has been undesirable to provide a key locking system for the door wherein the door is mechanically locked on operation of the key. This feature has even been more undesirable when the automatic door opener is a radio controlled automatic door opener. The reason for the undesirable provision of a key locking means is that once the door is key locked the automatic door opener can be accidentally or unwantingly placed in operation to open the door. If this occurs then the electric motor means used to open the door is locked and thus the motor draws a stalling current. This current is sufficient to burn out the motor and as a consequence initiate a fire. The present invention has been devised to provide a means whereby the door and automatic door opening system can be key locked closed and wherein if the automatic door opener is accidentally or unwantingly operated then there will be no damage to the motor means.